An arched window covering comprising a panel (e.g., having a series of elongated cells) positioned in a fan arrangement defining a central space near a center of rotation of the fan arrangement, a base positioned in the central space, and a support member supported by the base and positioned to provide support to the panel. Preferably, the arched window covering further comprises a rail secured to at least one of two ends of the panel. In one embodiment, the base defines an opening adapted to receive the support member. The support member preferably comprises an elongated member extending from the base toward a radially outer portion of the panel, and a spacer member supported by the elongated member and adapted to hold the elongated member spaced from the panel. In one arrangement, a position of the spacer member relative to the elongated member is adjustable.